The Nordyne 669568R is a thermal expansion valve (TXV) specifically designed for 4-ton HVAC systems that utilize R410A refrigerant. Made of copper for durability, it features sweat or braze connections for convenient installation into refrigerant lines. This valve plays a critical role in regulating the flow of refrigerant into the evaporator coil. https://www.partshnc.com/669568r-nordyne-r410a-txv-4ton